How to implement Login with Apple in Node JS

Step 1: Set Up an Apple Developer Account

To implement Apple Login, you need to have an Apple Developer account. Follow these steps:

1. Go to the Apple Developer website (**https://developer.apple.com/**).
2. Sign in to your Apple Developer account or create a new one.
3. Navigate to the "Certificates, Identifiers & Profiles" section.
4. Create an "App ID" for your application, enabling the "Sign in with Apple" capability.
5. Generate a private key associated with your App ID.
6. Register a redirect URI for your application.

Step 2: Set Up the Node.js Project

Start by setting up a new Node.js project using a package manager like npm or yarn. Run the following command in your terminal:

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npm init

This will create a package.json file to manage your project's dependencies.

Step 3: Install Required Packages

To implement Apple Login in Node.js, we need to install the necessary packages. Run the following command in your terminal:

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npm install express axios jsonwebtoken

This will install Express.js, a popular Node.js web framework, the axios package for making HTTP requests, and the jsonwebtoken package for working with JSON Web Tokens (JWT).

Step 4: Implement the Authentication Routes

Create a new file, authRoutes.js, to define the authentication routes for your application. In this file, implement the routes for initiating the Apple Login flow, handling the callback URL, and logging out the user.

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const express = require('express');
const axios = require('axios');
const jwt = require('jsonwebtoken');
const router = express.Router();

const TEAM_ID = 'YOUR_TEAM_ID';
const CLIENT_ID = 'YOUR_CLIENT_ID';
const KEY_ID = 'YOUR_KEY_ID';
const PRIVATE_KEY = `-----BEGIN PRIVATE KEY-----\\nYOUR_PRIVATE_KEY\\n-----END PRIVATE KEY-----`;

// Initiates the Apple Login flow
router.get('/auth/apple', (req, res) => {
  const scope = 'email name';
  const state = 'YOUR_STATE';
  const redirectUri = 'YOUR_REDIRECT_URI';

  const authorizationUri = `https://appleid.apple.com/auth/authorize?response_type=code id_token&client_id=${CLIENT_ID}&redirect_uri=${redirectUri}&state=${state}&scope=${scope}&response_mode=form_post`;

  res.redirect(authorizationUri);
});

// Callback URL for handling the Apple Login response
router.post('/auth/apple/callback', async (req, res) => {
  const { code, id_token } = req.body;

  try {
    // Verify the id_token
    const applePublicKey = await axios.get(`https://appleid.apple.com/auth/keys`);
    const decoded = jwt.verify(id_token, applePublicKey.data, { algorithms: ['RS256'] });

    // Code to handle user authentication and retrieval using the decoded information

    res.redirect('/');
  } catch (error) {
    console.error('Error:', error.message);
    res.redirect('/login');
  }
});

// Logout route
router.get('/logout', (req, res) => {
  // Code to handle user logout
  res.redirect('/login');
});

module.exports = router;

Make sure to replace 'YOUR_TEAM_ID', 'YOUR_CLIENT_ID', 'YOUR_KEY_ID', and 'YOUR_PRIVATE_KEY' with your own credentials obtained from your Apple Developer account.

Step 5: Set Up the Express.js Server

In your main server file (e.g., app.js), import the required packages and configure the Express.js server. Include the authentication routes defined in authRoutes.js.

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const express = require('express');
const authRoutes = require('./authRoutes');

const app = express();

app.use(express.urlencoded({ extended: true }));
app.use('/', authRoutes);

// Start the server
app.listen(3000, () => {
  console.log('Server started on port 3000');
});

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